Characterization of group A streptococci causing invasive diseases in Sri Lanka

  1. Madumali Weerasekara
  2. Gihani Vidanapathirana
  3. Carmen Li
  4. Asanka Tennegedara
  5. Rasadanie Dissanayake
  6. Asela Ekanayake
  7. Muditha Abeykoon
  8. Mahen Kothalawala
  9. Veranja Liyanapathirana
  10. Margaret Ip

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Abstract

Group A β haemolytic streptococcus (GAS) or Streptococcus pyogenes is a human pathogen that causes an array of infections, including pharyngitis, cellulitis, impetigo, scarlet fever, toxic shock syndrome, and necrotizing fasciitis. The present study characterizes 51 GAS isolates from invasive infections in Sri Lanka, focusing on resistance profiles, genetic determinants of resistance, and virulence markers. Isolates were tested for sensitivity to penicillin, erythromycin, clindamycin, and tetracycline. The presence of erm (A), erm (B), and mef (A) was detected in erythromycin-resistant isolates, while tet (M) was detected in the tetracycline-resistant isolates. PCR was used to identify SpeA, SpeB, SpeC, SpeF, SpeG, smez , and ssa as virulence markers. Selected GAS isolates were emm -typed using the updated CDC protocol. All 51 isolates were susceptible to penicillin. The number of isolates non-susceptible to erythromycin was 16. The commonest resistance determinant identified was erm (B) (11/16). Tetracycline non-susceptibility was found in 36 (70.6 %) isolates and 26 of them contained the tet (M) gene. Thirteen (25.5 %) isolates were resistant to both tetracycline and erythromycin, while 12 (23.5 %) isolates were sensitive to both antibiotics. The commonest virulence markers detected among the isolates were SpeB (44, 86.3 %), SpeG (36, 70.6 %), and SpeF (35, 68.6 %), while SpeJ (15, 29.4 %), SpeA (10, 19.6 %), and ssa (5,9.8 %) were less common. The emm types were diverse. In conclusion, the GAS isolates studied showed resistance to erythromycin and tetracycline, while retaining universal susceptibility to penicillin. Additionally, these isolates exhibited diverse genetic backgrounds, displaying varying patterns of virulence genes and emm types.

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  1. Version published to 10.1099/acmi.0.000697.v4 on Access Microbiology
  3. Version published to 10.1099/acmi.0.000697.v3 on Access Microbiology
  5. Access Microbiology

    Comments to Author

    I have gone through the all the edits, further change would not be possible as you lack major data in your study. I agree with your response

    Please rate the manuscript for methodological rigour

    Satisfactory

    Please rate the quality of the presentation and structure of the manuscript

    Good

    To what extent are the conclusions supported by the data?

    Partially support

    Do you have any concerns of possible image manipulation, plagiarism or any other unethical practices?

    No

    Is there a potential financial or other conflict of interest between yourself and the author(s)?

    No

    If this manuscript involves human and/or animal work, have the subjects been treated in an ethical manner and the authors complied with the appropriate guidelines?

    Yes

  6. Access Microbiology

    Comments to Author

    I appreciate the authors for considering critical criticism and revising the manuscript. However, I suggest authors revise the paper as there is still room for improvement in sections like methods, results, discussion, and conclusion. Results sections still need to be rewritten, started with a table, and have no description of the data. Authors can consider combining results and discussion in cases of limited data or word restrictions. Please include limitations of the study, such as clinical data, but not reasons like lack of funding. The ethical statement can be included in the methods section. The conclusion can be elaborated with future scientific implications of the study; I suggest not including tourism as an implication. The Abstract and Conclusion sections have similar wording; please revise. Change spelling of "prevelant" in Abstract to "prevalent". I suggest authors read carefully and check for spelling mistakes throughout the manuscript, which does not require any paid sources or funding to correct them, to consider for publication. Abstract:In conclusion, resistance to erythromycin and tetracycline is prevelant in GAS isolates in Sri Lanka while the universal susceptibility to penicillin remained unchanged. Further, these isolates are from diverse backgrounds with different occurance patterns of virulence genes and emm types. Conclusion: We have demonstrated that while the universal susceptibility to penicillin remains, resistance to erythromycin and tetracycline is prevalent in GAS isolates in Sri Lanka. Further, these isolates are from diverse backgrounds with different patterns of virulence genes and emm types. I sincerely suggest authors revise the manuscript presentation by reviewing the previously published short communications in Access Microbiology to improve readability.

    Please rate the manuscript for methodological rigour

    Satisfactory

    Please rate the quality of the presentation and structure of the manuscript

    Poor

    To what extent are the conclusions supported by the data?

    Partially support

    Do you have any concerns of possible image manipulation, plagiarism or any other unethical practices?

    No

    Is there a potential financial or other conflict of interest between yourself and the author(s)?

    No

    If this manuscript involves human and/or animal work, have the subjects been treated in an ethical manner and the authors complied with the appropriate guidelines?

    Yes

  7. Version published to 10.1099/acmi.0.000697.v2 on Access Microbiology
  9. Access Microbiology

    Comments to Author

    The study has some value by identifying the GAS strain classification for resistance and susceptibility. However, the way the article was presented was extremely inadequate, with an utterly poor presentation of results; therefore, unless it is completely changed and adheres to journal format, I would want to suggest a REJECTION. The strain names were not italicized all over the manuscript. Authors should elaborate on their methodology section instead of writing one-line sentences. I recommend putting together the list of 51 isolates collected, their sources, and rationalizing the resistance and susceptibility of strains and the disease locations of humans rather than the location of the country. I recommend authors show representative images of antibiotic disc analysis. Why do the figure and table have no detailed caption or axis name for the horizontal axis? Poor display of results. Revise the second paragraph on page 7 instead of writing in single lines. What is the relevance of discussing different countrie's GAS isolates with Sri Lankan samples? The authors should highlight the significance of the GAS classification of Sri Lankan samples. Overall, the manuscript is significantly lacking in journal ethics and writing. I recommend authors go through previous publications in journals and compare them to revise the overall manuscript.

    Please rate the manuscript for methodological rigour

    Satisfactory

    Please rate the quality of the presentation and structure of the manuscript

    Poor

    To what extent are the conclusions supported by the data?

    Partially support

    Do you have any concerns of possible image manipulation, plagiarism or any other unethical practices?

    No

    Is there a potential financial or other conflict of interest between yourself and the author(s)?

    No

    If this manuscript involves human and/or animal work, have the subjects been treated in an ethical manner and the authors complied with the appropriate guidelines?

    Yes

  10. Access Microbiology

    Comments to Author

    "Methodological rigour, reproducibility and availability of underlying data" 1. Demographics of the population are not described in this manuscript. What were the baseline characteristics of the population, male/ female ratio, age group, comorbidities if any. Elaborate in more detail about inclusion and exclusion criteria. 2. You have mentioned invasive Group A streptococcal infection, please add an operational definition explaining which infection was considered as "invasive". 3. You have not mentioned how data was retrieved 4. Which software was used to find statistical significance "Presentation of results" 1. While reading about sensitivities of antibiotics, and percentage resistance , it's difficult to interpret which particular group is being discussed. Like you have mentioned 16 were resistant to erythromycin and out of which 11 had ermB gene, 1 had mefA gene, 1 had both ermB and mefA and one had none, it makes total 17 not 16. It's better if you could depict this result in a tabulated form or a flow chart form so the reader has a clear idea about the exact number of resistant/sensitive cultures out of total 51. Similar difficulties in interpreting other groups. 2. You have not mentioned outcomes of the patients, how these patients were managed, and what is the clinical impact of carrying a resistant gene. you have mentioned only one benefit of molecular typing this bacteria, which is vaccine production. I think a reader should know the clinical impact of carrying this resistant bug which can be shown as different outcomes of these patients and morbidity/mortality. "How the style and organization of the paper communicates and represents key findings" Overall this paper style and organization is good, with inclusion of heading and covering all important aspects of a manuscript. However, adding some more figures, as I mentioned above, would be beneficial and make it more attractive. "Literature analysis or discussion" 1. You've presented data on antibiotic resistance, which is essential. However, you could delve further into the implications of these findings. For example  why is it important to study antibiotic resistance in GAS?  What are the potential clinical implications,  How might this relate to global trends?  Consider discussing the clinical significance of GAS resistance patterns 2. You've discussed the prevalence of virulence markers, but it would be valuable to discuss their potential roles in GAS pathogenicity. Explain why some virulence markers are more prevalent than others and their significance in disease development. 3. As this research was partially funded, you have not mentioned bias which might have occured due to this funding, It should be discussed in your limitation

    Please rate the manuscript for methodological rigour

    Satisfactory

    Please rate the quality of the presentation and structure of the manuscript

    Good

    To what extent are the conclusions supported by the data?

    Strongly support

    Do you have any concerns of possible image manipulation, plagiarism or any other unethical practices?

    No

    Is there a potential financial or other conflict of interest between yourself and the author(s)?

    No

    If this manuscript involves human and/or animal work, have the subjects been treated in an ethical manner and the authors complied with the appropriate guidelines?

    Yes

  11. Version published to 10.1099/acmi.0.000697.v1 on Access Microbiology